Communication
Positioning via digital I/Os
234
192-120101 N11 C3I11T11 November 2007
5.1.3.
Binary record
The binary record with block securing is based on 5 different telegrams:
2 request telegrams which the control sends to Compax3 and
3 response telegrams which Compax3 returns to the control.
Telegram layout
Basic structure:
Start code
address
Number of data bytes - 1
Data
block securing
SZ A L
D0
D1
...
D
n
Crc(Hi)
Crc(Lo)
The start code defines the frame type and is composed as follows:
Bit
7
6
5
4
3
2
1
0
Frame type
Frame identification
PLC
Gateway
address
RdObj
Read
object
1 0 1 0 x 1 x
x
WrObj
Write
object
1 1 0 0 x 1 x
x
Rsp Answer
0 0 0 0 0 1 0
1
Ack Positive
command
acknowledgement
0 0 0 0 0 1 1
0
Nak Negative
command
acknowledgement
0 0 0 0 0 1 1
1
Bits 7, 6, 5 and 4 of the start code form the telegram identification; Bit 2 is always
”1”.
Bits 3, 1 and 0 have different meanings for the request and response telegrams.
The address is only necessary for RS484.
-> Compax3
the address bit (Bit 0 = 1 ) shows if the start code is followed by an address
(only for RS485; for RS232 Bit 0 = 0)
the gateway bit (Bit 1 = 1) shows if the message is to be passed on.
(Please set Bit 1 = 0, as this function is not yet available)
the PLC bit (Bit 3 = 1 ) allows access to objects in the PLC/Pop format
U16, U32: for integer formats (see bus formats: Ix, Ux, V2)
IEEE 32Bit Floating Point: for broken formats (bus formats: E2_6, C4_3, Y2, Y4;
without scaling)
With Bit 3 = 0 the objects are transmitted in the DSP format.
DSP formats:
24 Bit = 3 Bytes: Integer INT24 or Fractional FRACT24
48 Bit = 6 Bytes: Real REAL48 (3 Byte Int, 3 Byte Fract) / Double Integer DINT48
/ Double Fractional DFRACT48
Request telegrams
